a) If this is something marmotlord wants why are you the one complaining not him?
b) He can make 30 different storygames in the same "world".
c) It appears he's only found two co-authors so far anyways.
d) The chance that game will ever be finished is extremely small.
e) You can have different co-authors at different times and get around the limit that way.
f) It's very difficult to keep a story consistent with that many authors, as people are likely to contradict each other.